Three Marines, including the suspected gunman, are dead after a shooting at Marine Corps Base Quantico in Virginia.

The suspected shooter, a male Marine, was killed from an apparently self-inflicted gunshot wound after he allegedly shot and killed another male and a female Marine. Authorities found the suspect's body inside a barracks building near the Officer Candidates School early this morning, Lt. Agustin Solivan told ABC News.

All three were active-duty Marines assigned to Officer Candidates School and pronounced dead at the scene, Col. David W. Maxwell, base commander at Quantico, said this morning at a news conference.

The three Marines were junior-enlisted Marines who worked as training personnel at the school, a Department of Defense official told ABC News.

Maxwell said, "On behalf of Marine Base Corp Quantico and the Officer Candidates School, I want to express my sincere condolences to the families, friends and of the three marines we lost night. My thoughts and prayers are with them at this time."

The Marine base at Quantico is a sprawling training facility located 37 miles south of Washington. It is also home to the FBI's Training Academy.

A 911 call was received by the Provost Marshal's office about 10:30 p.m. William County Police and military officials responded and were on the scene within five minutes, but did not report hearing any shots fired, Maxwell said.

The shooting, Maxwell said, occurred at Taylor Hall, a single barracks at the Officer Candidates School.

All base residents and employees were notified to remain indoors and keep their doors locked.

Contrary to previous information distributed by the Marine base, there was no standoff or barricade around the shooter, Maxwell said.

The lockdown of the base was lifted at about 2:30 a.m. today.

"Marine Corps Base Quantico is Code Green at this time," Quantico said on Twitter. "All normal activities are cleared to resume."

The identities of the victims will be withheld until the families are notified, said Maxwell, who expects a lengthy investigation into the shooting.

"This is truly a tragic loss for the Marine Corps, which has had a number of tragic losses in the last couple of weeks," Maxwell said.

Seven Marines were killed Monday in a training accident at the Hawthorne Army Depot in Nevada when a mortar round exploded.